On multivariate analysis, slow‐metabolizing ADH1B (hazard ratio [HR] 2.21; 95% confidence interval [CI] 1.1–4.45) and inactive ALDH2 (HR 3.28; 95% CI 1.28–11.15) were significant predictors of the development of metachronous esophageal SCC or head and neck SCC. This evidence concerns the gene ADH1B and esophageal squamous cell carcinoma.